1. Field of the Invention
The present invention relates to rechargeable batteries as for example, a nickel-cadmium cell battery, and chargers therefor.
2. Prior Art
In recent years, rechargeable battery operated devices have become more and more commonplace and today are used in such devices as hand tools, vacuum cleaners, flashlights, and numerous others. Such devices usually utilize "secondary cells" as for example a nickel-cadmium cell that, when its potential is depleted, can be recharged or regenerated through application of an electrical current in the direction opposite to the cells discharge flow path. Charging periods for such secondary cells can vary with the circuits employed.
The present invention is an improvement on an earlier patent issued to the inventor on a combination battery and recharger, U.S. Pat. No. 3,360,708. This patent provided, as separate units, a rechargeable battery cell and a recharging circuit therefor and for alternatively coupling the two components. In one coupled arrangement, the unit is to function as a battery, and in the other arrangement, the unit is to be plugged into a standard wall socket, connecting a charging circuit to recharge the battery cell. The present invention, significantly different therefrom eliminates the two separate housings and includes both the nickel-cadmium cell and charger unit within a single housing. The invention further includes a single coupling head for alternative arrangement to the single housing to connect the cell as a battery, or for plugging into a conventional electrical socket to connect the nickel-cadmium cell to a standard electrical current for recharging. Additionally, where the earlier charger and battery were separate units and the one could easily be separated from the other, the present invention, provides a releasable stud end and/or socket type connector for locking the coupling head to the single housing top.
The present invention improves upon the circuitry set out as preferred in the earlier patent by utilizing an inexpensive and efficient capacitance circuit. This circuit provides for coupling the charging circuit to the nickel-cadmium cell during both charging and discharging, and includes a unique disconnect arrangement for isolating the battery base (negative pole) during charging. The circuit arrangement provides an efficient charger circuit that is inexpensive to produce, is superior to the earlier utilized resistance circuit and is therefore a significant improvement.